drm/i915: Reduce hangcheck frequency

By reducing the hangcheck frequency we check less often, conserving
resources, and still detect a lock up quickly. On a fast machine with a
slow GPU (like a Core2 paired with a 945G) it is easy for the hangcheck to
misfire as we check too fast.

Also once hung and if we fail to completely reset the chip, we have a
nasty habit of proclaming a hang many times a second and generating a
strobe-like display.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index bc8438d..e64b8ea 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -328,7 +328,8 @@
 		trace_i915_gem_request_complete(dev, seqno);
 		DRM_WAKEUP(&dev_priv->render_ring.irq_queue);
 		dev_priv->hangcheck_count = 0;
-		mod_timer(&dev_priv->hangcheck_timer, jiffies + DRM_I915_HANGCHECK_PERIOD);
+		mod_timer(&dev_priv->hangcheck_timer,
+			  jiffies + msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
 	}
 	if (gt_iir & GT_BSD_USER_INTERRUPT)
 		DRM_WAKEUP(&dev_priv->bsd_ring.irq_queue);
@@ -1018,7 +1019,8 @@
 			trace_i915_gem_request_complete(dev, seqno);
 			DRM_WAKEUP(&dev_priv->render_ring.irq_queue);
 			dev_priv->hangcheck_count = 0;
-			mod_timer(&dev_priv->hangcheck_timer, jiffies + DRM_I915_HANGCHECK_PERIOD);
+			mod_timer(&dev_priv->hangcheck_timer,
+				  jiffies + msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
 		}
 
 		if (HAS_BSD(dev) && (iir & I915_BSD_USER_INTERRUPT))
@@ -1394,7 +1396,8 @@
 
 out:
 	/* Reset timer case chip hangs without another request being added */
-	mod_timer(&dev_priv->hangcheck_timer, jiffies + DRM_I915_HANGCHECK_PERIOD);
+	mod_timer(&dev_priv->hangcheck_timer,
+		  jiffies + msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
 }
 
 /* drm_dma.h hooks